They can get an unknown for all I care. I'm just hoping Ultron's look is close to the classic look in the comics. I don't want them straying too far from that appearance.

I don´t think they will do that. What would be the point? They can´t name it Age of Ultron if Ultron is not going to be comics-Ultron in some way.
Some of the classical features will be there, not all maybe, but most.